I have iron def anaemia. colonoscopy result ok, fobt +ve for blood am waiting for capsule endoscopy result. what may cause microscopic blood loss?

Bleeding.: Agents that cause inflammation of the gut, eg aspirin, anti-inflamatory drugs, alcohol, endocrine disease-addisons disease and cushings disease; parasites, stomach acid or gall bladder reflux into the esophagus; (rare) tumors of the small bowel including acid secreting tumors. Are you iron deficient from bleeding or nonabsorption?

Causes: Colonoscopy looks only at the colon, rectum and a tiny part of the small intestine. Bleeding can come from the small intestine, or an area that was not well seen on colonoscopy. Alternatively, anemia can be due to menstrual bleeding. Last thing is that some blood cancers cause anemia too, but this is rarer. A double-ballon endoscopy can often find the small bowel bleeding sources.